Mountain climbers: Start in a plank position and alternate bringing your knees to your chest as quickly as possible.
Jumping jacks: Jump your feet out and raise your arms overhead, then jump back to starting position.
Burpees: Start in a standing position, then squat down and kick your feet back into a plank position, do a push-up, jump your feet back to your hands, and stand back up.
Jump rope: Jump over an imaginary rope as quickly as possible.
High knees: Run in place while bringing your knees up to your chest as high as possible.